A few comments,
The leader of the Meetup group has removed my original comment to his event which made him and those who signed up aware of the wilderness regulation. He has subsequently edited the announcement to acknowledge the group size of 10. Thus something good may have come out of this. Unfortunately tweaking the group size to 100 pretty well establishes that he doesn't accept constructive input and tends to reinforce the New Yorker stereotype.
There is a fundamental disconnect on dispersing a group without telling folks in advance. I would expect that far more folks would tend to sign up for a group Pemi loop rather than doing it as unsupported solo event. Effectively if the group disperses, it becomes a semi supported solo event. Unless the participants are well vetted, some will go slower and possibly have to bail at some point. Thus without technology like Spot, the group leader really does not know how many people are actually still on the trail hiking after he/or she is sitting in the parking lot or campground having a few beers. As the group will be dispersed, will there be a sweep team to assist folks who are injured or incapacitated by such common things as hypothermia or dehydration/heat stroke? Even if there is sweep team, how will they know if an individual took the wrong turn or stepped off in the woods when they pass? From a group management perspective, its far easier to hike as a group and stay as group with the possibility that if a participant does have issues, someone else can volunteer to cut their day short and escort the hiker out. Of course that trips the group of 10 rule.
Unfortunately many Meetup participants assume that the person posting the trip is knowledgeable of the terrain and potential risks and is handling all the details and they just show up for the hike. This works unless the leader is clueless, a somewhat publicized example is one of the HVH hike leaders who set up a trip in the Mahoosucs and decided to take a short cut and ended up on the wrong side of the ridge at the end of a dead end road at dusk, 35 miles away for their groups car. In the New Hampshire area is another group whose leader had for a fairly long period of time adopted the survival of the fittest strategy and would have relatively large group sizes (20 to 30) wherein he would take up with his select group at their own pace and leave the rest of the group to fend for themselves. The group is still around with a very large membership and is very active running multiple hikes most weekends.
I actively participate in Meetup and am a trip leader on occasion. It tends to be a gateway for many to getting into the outdoors for the first time or getting back in. Somewhat like VFTT was long ago, it was low commitment way of joining a group and gaining some skills and meeting like minded individuals. I realize that many long term VFTT folks tend to only hike within their facebook group but the downside is that this tends to be exclusionary to new people who might want to head out hiking as they are probably not aware of the particular facebook group that they could join.
The downside to any group hike is many folks learn by doing and if the leader is doing the wrong thing, the participants are learning the wrong thing and reapplying it on future hikes, thus the importance of the leader to try to follow the rules and letting the members know why.
I personally avoid large Meetup groups and find the size limitation of group of 10 is pretty effective. It is difficult to manage the group size as there are many folks who sign up and no show, thus a group of 10 signed up may yield a group of 4 hikers. Thus some leaders intentionally enlarge the group size to accommodate the no shows.
The forest service group size regulations tend to be fairly vague and leave a lot of judgment on the part of the FS employee. The regulations are intended as a management tool rather than a enforcement tool. Baxter State Park had to modify their regulations last year to be quite specific when some groups started to try to work around them "2.1. The maximum size of hiking groups shall be 12 persons. Affiliated groups on the same trail separated by less than one mile shall be considered one group." This change was reportedly made when groups would discharge a large group at a trail head and then would disperse the group by starting at staggered intervals, generally they would rapidly become a large group again.
Long ago I discussed the group size rules with a FS employee and she indicated that any organized activity with more than 10 participants even if they were well dispersed was inherently a group and thus banned from a wilderness area. The inquiry was made for a possible fundraiser where dispersed individuals would collect pledges and walk to a specific point through a wilderness area. While discussing this, the point was brought up that this specifically included other dispersed activities such as races and competitions. For several years when the Lincoln Woods cabin was staffed by FS, every group over 10 was challenged if they tried to cross the bridge and groups were turned back if they were over 10 or did not have an outfitter guide card. In many other spots in the whites at the same time, bus loads of youth groups routinely were hiking Tuckermans. It all comes down to the forest supervisor or the district ranger on what priorities are to be enforced by their staff. The FS employee is long gone and I expect over the 20 years the enforcement priorities have changed repeatedly.
